1. Field of the Invention
The present invention generally relates to a disk device. Specifically, the present invention relates to a disk device having a shock absorbing component for an optical pickup.
2. Background Information
A conventional disk device includes an optical pickup for scanning a disk recording face of a disk and a power transmission mechanism. The optical pickup includes a light emitting element, a light receiving element, an objective lens and an optical base. The light emitting element, the light receiving element and the objective lens are assembled in the optical base. The power transmission mechanism includes a screw shaft that is rotationally driven at a fixed position by a motor, and a movable unit that has teeth that mesh with the screw shaft. The movable unit is linked to the optical base of the optical pickup, constituting part of the optical pickup. The power transmission mechanism converts the rotational motion of the screw shaft into the linear motion of the movable unit, and transmits the motion to the optical pickup.
The optical base of the optical pickup has a slide bearing and a slider. The slide bearing is slidably mated to a guide shaft attached to a frame. The slider follows a countershaft that is also attached to the frame. The drive force transmitted by the power transmission mechanism causes the optical pickup to be guided by the guide shaft and the countershaft and travel a linear path in the forward and backward directions. A turntable is attached to the frame. The recording face of the disk rotating along with the turntable is optically scanned by the optical pickup.
With the conventional disk device, the normal range of travel of the optical pickup, or the range of travel of the optical pickup during normal recording or reproduction (effective travel range) falls within the range in which the teeth of the movable unit mesh with the teeth by the electrical control of the rotational direction, the number of rotations and the rotational speed of the motor. Therefore, under suitable electrical control, the optical pickup does not move outside of the effective travel range and collide with the frame.
If the disk device should be subjected to a heavy impact for some reason when the disk device is being transported or moved, such as when the device is dropped, the teeth of the movable unit moves outside of the effective travel range of the optical pickup while rotating the screw shaft, and disengage to the spiral groove in the screw shaft. As a result, the position where the two mesh deviates from the normal position, which prevents proper recording or reproduction operation.
In view of this, a protrusion is provided to one end of the movable unit, so that if the optical pickup runs outside of the effective travel range, the protrusion is received by a receiver provided on the frame, thereby preventing the runaway movement.
Meanwhile, another conventional disk reproduction device cushions the impact when a pickup that has reached the inner or outer periphery of the disk collides with a component on the chassis. The conventional disk reproduction device includes an elastic contact tab with a cantilever shape formed on a bracket. The bracket has a support tab for forcibly pushing on the end of the guide shaft and supporting the guide shaft on the chassis. The contact tab receives the pickup (see Japanese Laid-Open Patent Application No. H11-66770, for example).
Also, with another optical pickup drive mechanism, the optical pickup drive mechanism meshes with a lead screw and converts the rotational motion of the lead screw into the linear motion of the optical pickup. Furthermore, the optical pickup drive mechanism includes a means for shortening the seek time of the optical pickup (see Japanese Laid-Open Patent Application No. 2002-216441, for example).
Furthermore, another disk device includes a means for maintain a meshed state between a spiral groove of a lead screw and an engagement component of a rack that has undergone tilt adjustment (see Japanese Laid-Open Patent Application No. 2005-235263, for example).
With the conventional disk device, the protrusion received by the receiver on the frame is provided to the movable unit to prevent runaway movement of the optical pickup to outside the effective travel range as a result of impact from being dropped, etc. However, the impact when the protrusion collides with the receiver on the frame tends to affect the entire optical pickup directly, and this can adversely affect assembly precision of the optical components of the optical pickup assembled on the optical base, which prevents proper recording or reproduction operation.
In view of this, it is possible to adopt the approach used in Japanese Laid-Open Patent Application No. H11-66770, in which the elastic contact tab is provided to the bracket attached to the chassis to cushion the impact during collision of the optical pickup, which reduces the loss of initial assembly precision of the optical components assembled on the optical base.
However, with this arrangement, it is difficult to obtain an effective cushioning action if the elastic constant of the contact tab is too small. On the other hand, if the elastic constant is too large, it is difficult to absorb the impact effectively, which makes it difficult to obtain the effective cushioning action. Accordingly, there are many limitations regarding the proper setting of the elasticity of the contact tab. As a result, it is difficult to obtain an effective cushioning action with the cantilevered contact tab. Also, this approach requires extra parts, such as the contact tab and fastening screws used to attach the contact tab to the chassis. Thus, there is a corresponding increase in the number of parts, and this complicates the assembly process.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved disk device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.